Generate make-fai-nfsroot.conf and nfsroot.conf on-the-fly

FAI 4 uses nfsroot.conf instead of make-fai-nfsroot.conf without
providing any backwards compatibility. :( So while at it rework
the way how make-fai-nfsroot.conf is handled:

* No longer ship /etc/grml/fai/make-fai-nfsroot.conf at all
* Generate nfsroot.conf based on default settings (can be overriden
  by $FAI_DEBOOTSTRAP + $FAI_DEBOOTSTRAP_OPTS) on the fly
* Provide symlink make-fai-nfsroot.conf pointing to nfsroot.conf
  to support old and new FAI versions at the same time
* After execution copy generated nfsroot.conf file to log directory
  and get rid of make-fai-nfsroot.conf and nfsroot.conf in
  $GRML_FAI_CONFIG (/etc/grml/fai/ by default) afterwards

Note: existing make-fai-nfsroot.conf files will be moved
to make-fai-nfsroot.conf.outdated to avoid possible data loss.

Closes: https://github.com/grml/grml-live/issues/4
Generate /etc/grml_live_version after FAI execution + drop /etc/dpkg/dpkg.cfg.d/unsafe-io code

FAI uses /etc to detect whether a chroot exists or not and will
skip debootstrap stage if /etc exists already. This causes serious
problems if the user doesn't have a BASEFILE, therefore we can't
edit files inside /etc before running FAI. :(

As a result:

1) generate /etc/grml_live_version *after* FAI has been executed

2) drop /etc/dpkg/dpkg.cfg.d/unsafe-io related code.
As stated in commit 9269536ba7bb7def8664972d153b71d193450595

| Enable --force-unsafe-io for dpkg
|
| While this might help on resource constrained systems, no performance
| impact has been measured during an unscientific test on a well-geared
| machine.

it does not seem to be that relevant. But even more important: it
doesn't work for systems without BASEFILEs because FAI skips the
debootstrap stage if /etc exists already, so we can't generate
/etc/dpkg/dpkg.cfg.d/unsafe-io *before* running FAI. Unless
someone comes up with benchmarks about real performance impacts
let's skip adding more fcopy logic...
Drop unused NFSROOT configuration file
Include linux16.mod in GRUB image file x86_64-efi.img

Otherwise [U]EFI systems will fail on some addons because of:

| Grub cannot load `linux16.mod`

Thanks: Paul Menzel for the bug report
Thanks: Ulrich Dangel for the bugfix
Revert "Include linux16.mod in GRUB image file x86_64-efi.img"

This reverts commit bf8e3bc45b72c51386b53da9fe5acae2703b6e41.
Breaks grml-live:

| =====   shell: GRMLBASE/45-grub-images   =====
| grub-mkimage: error: cannot stat /usr/lib/grub/x86_64-efi/linux16.mod.
| GRMLBASE/45-grub-images FAILED with exit code 1.

See http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=651562 for
the reason why /usr/lib/grub/x86_64-efi/linux16.mod doesn't exist.
SW: add sysstatt to GRML_FULL

Thanks: Michael Renner for reporting
Use syslinux's mboot.c32 for booting Grub2

This fixes the broken Grub2 boot entry on 64bit systems.

Thanks: Jordan Uggla for his valuable bootloader knowledge
umount_all: also get rid of loopback mount of ISO
extract ISO feature: make sure *.squashfs files exist + support older ISOs too

ISOs before release 2011.12 used /live/ for storing squashfs files,
releases starting with 2011.12 use /live/*/ (where "*" corresponds
to the release name). Test whether such files exist before accessing
them and while adding the check also add support for releases older
than 2011.12.

Thanks: Charles A. Hewson <cahewson@eskimo.com> for the bugreport
Release new version 0.19.2
SW: drop firmware-linux-free + firmware-linux-nonfree from GRML_FULL

Addressing:

| dpkg: error processing /var/cache/apt/archives/firmware-linux-free_3_all.deb (--unpack):
|  trying to overwrite '/lib/firmware/keyspan_pda/keyspan_pda.fw', which is also in package linux-image-3.3.0-3-grml-amd64 3.3.7-1+grml.1
| dpkg: error processing /var/cache/apt/archives/firmware-linux-nonfree_0.35_all.deb (--unpack):
|  trying to overwrite '/lib/firmware/e100/d101m_ucode.bin', which is also in package linux-image-3.3.0-3-grml-amd64 3.3.7-1+grml.1

If there are any firmware files from firmware-linux-free
or firmware-linux-nonfree that we need to ship (like the
ones for radeon) we need to find a different way...
SW: remove firmware-qlogic from GRML_FULL

Addressing jenkins grml64-full_testing #150:

| dpkg: error processing /var/cache/apt/archives/firmware-qlogic_0.35_all.deb (--unpack):
|  trying to overwrite '/lib/firmware/qlogic/1280.bin', which is also in package linux-image-3.3.0-3-grml-amd64 3.3.7-1+grml.1
Revert "SW: drop firmware-linux-free + firmware-linux-nonfree from GRML_FULL"

This reverts commit dda6a44ba1325a176dc1e0f7020b32f03cf3b052.

New kernel build is supposed to fix this issue.
Revert "SW: remove firmware-qlogic from GRML_FULL"

This reverts commit 588ee25553bd316a5c3c2595fac421281d36c9c7.

New kernel build is supposed to fix this issue.
Merge remote-tracking branch 'upstream/master'

his merge is necessary,